The Court of Appeal has underlined the importance of litigants proving a causal connection in negligence cases. The appeal, Ediger v. Johnson, 2011 BCCA 253, involved injuries sustained by Cassidy Edgar during her birth on 24 January 1998. The plaintiff suffered damage to her central nervous system caused by inadequate oxygen flow due to compression of the umbilical cord (fetal bradycardia). At issue was whether the actions of the obstetrician caused the injuries sustained by the plaintiff.

The trial judge reasoned that although the precise mechanics of how the attempted forceps procedure caused the cord compression was not established on the evidence, the temporal connection between the procedure and the onset of the fetal bradycardia was sufficient to reasonably infer that a causal connection existed between the two events. However, the Court of Appeal found that the trial judge’s finding was not supported by findings of fact on the timing and sequence of events and was inconsistent with the undisputed medical evidence in the case. It further found it was not a case where an inference of causation could be drawn and dismissed the action.

In coming to its decision, the Court of Appeal reviewed the law as it relates to actions in negligence, affirming the authority of the so-called “but for” test:

Causation in negligence is determined by the “but for” test. The test requires the plaintiff to prove, on a balance of probabilities, that “the injury would not have occurred but for the negligence of the defendant”…

There are two aspects to the causation inquiry. The first requires the plaintiff to identify the specific acts of negligence by the defendant that caused the specific harm to the plaintiff. This is sometimes referred to as the cause-in-fact (i.e., factual causation) of the plaintiff’s injuries and requires a substantial connection between the defendant’s negligent act and the harm to the plaintiff. The second aspect of the inquiry requires the plaintiff to establish the proximate cause between the defendant’s negligent conduct and the plaintiff’s loss or harm. This is sometimes referred to as the cause-in-law (i.e., legal causation) and requires the loss or harm caused by the negligent conduct to fall “within the range of that for which it is just to make the defendant responsible” …

… if the plaintiff cannot establish factual causation that ends the inquiry: without cause-in-fact, there can be no cause-in-law.

Referring to the authority of the Supreme Court of Canada case of Snell v. Farrell, the Court of Appeal further confirmed that where both parties have led expert evidence on the issue of causation (as they had in this case) it is not open to the court to apply “common sense” reasoning to draw an inference of causation:

In this case, the appellant led evidence to the contrary. While some potential causes for the cord compression were ruled out by the medical experts (including cord prolapse, placental abruption, and a short cord) there was also evidence that cord compression could occur from a “kink” in the cord or a nuchal cord, or in some instances for unknown reasons. The fact that the precise mechanism of how the cord compression occurred could not be determined did not lessen the burden of proof on the respondent or the trial judge’s task of having to weigh the evidence on causation in the context of her other findings of fact. The inference of causation from Snell was not available to be drawn. The trial judge had to determine whether the evidence established that, on a balance of probabilities, the appellant’s attempted forceps delivery was the cause of the cord compression.

In conclusion, the Court of Appeal stated that “absent a causal connection” between the doctor’s attempted forceps delivery and the cord compression the plaintiff’s action could not succeed.